package com.wang.sort;
//返回无序数组中最小值的下表
//二分查找  有序无序都可使用
public class Demo7_BSAwesome {
    public static int getLessIndex(int[] arr) {
        if( arr == null || arr.length == 0) {
            return -1;
        }
        if(arr.length == 1 || arr[0] < arr[1]){
            return 0;
        }
        if(arr[arr.length - 1] < arr[arr.length -2]){
            return arr.length - 1;
        }
        int left = 1;
        int right = arr.length - 2;
        int mid = 0;
        while (left <= right){
            mid = (left + right) / 2;
            if(arr[mid] > arr[mid - 1]){
                right = mid -1;
            }
            else if (arr[mid] > arr[mid + 1]){
                left = mid + 1;
            }
            else {
                return mid;
            }
        }
        return left;
    }
}
